How about this for a shower epiphany: Even though black holes are a core feature of the astronomical model of the universe, as well as a staple of sci-fi (plus a source of inspiration for a very sweet Muse album), nobody on Earth has ever directly observed one of them. Nobody. Never. But in the next few days, as the already-activated Event Horizon Telescope makes an attempt at directly observing the supermassive blackhole at the center of our Milky Way galaxy, that may finally cease to be the case.
Photographing a black hole—an object so massive that not even light can escape its gravitational pull—is, unsurprisingly, extremely difficult. Black holes, by definition, are “ideal black bodies that reflect no light,” making them just about the worst thing one would be tasked with photographing amidst the darkness of space. But hope for a direct glimpse of a black hole isn’t totally lost, because just before a black hole’s event horizon (or perimeter after which nothing can escape the pull of the black hole’s gravity) is an accretion disk of plasma that’s spinning around so fast that it becomes extremely hot and extremely bright, even emitting X-rays.
In an excellent TedX talk, MIT Ph.D. candidate Katie Bouman discusses how the Event Horizon Telescope aims to glimpse that hot, bright accretion disk, as well as the “shadow” of the supermassive black hole carved into it. “Getting this first picture will come down to an international team of scientists, an Earth-sized telescope, and an algorithm that puts together the final picture,” Bouman says in her talk above.
That Earth-sized telescope (larger telescopes can capture more light for better resolution) will actually be made up of an international network of telescopes, in places like Hawaii, Arizona, the South Pole, Chile, and Spain. These telescopes will, together, hopefully provide a very limited picture of the accretion disk around Sagittarius A*, which is the spot at the center of the galaxy (26,000 lightyears away from Earth) that is almost certainly a supermassive black hole four million times the mass of our Sun.
Motion of stars around Sagittarius A*
The idea of the Earth-sized telescope only works if there are telescopes completely covering Earth’s surface, however, which there are not. That’s where Bouman and advanced imagining techniques enter the picture—and also literally complete the picture using super-smart algorithms that compare the light received by the Event Horizon Telescope to images of known objects in order to fill out significant gaps.
There’s obviously no guarantee that the Event Horizon Team will find what they’re looking for between now and April 14 (end date for the campaign), but still, a picture of nothing could be worth an infinite number of words.
What do you think about this attempt at photographing a supermassive black hole? Let us know in the comments below!
Images: Wikimedia / NASA
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